Permanent magnet constituted of fine particles of a compound m5r



Aug. 11,1910 K H.J.BusH'ow Em 3,523,836

PERMANENT MAGNET CONSTITUTED OF FINE PARTICLES OF A COMPOUND M 3 Filed Jan. 19. 1968 2 Sheets-Sheet 1 erg 0e"gr' La Ce Co 0,2 0.4 0.5 0.8

FIG. I

INVENTOR.

K.H.J. BUSCHOW W.A .J.J- vac:

' AGENT Aug. 11, 1970- Filed Jan. 19. 1968 K. H. J. BUSCHOW ETAL PERMANENT MAGNET CONSTITUTED'OF FINE PARTICLES OF A COMPOUND M R 2 Sheets-Sheet 3 (BH)max IHC (0c) x e Co 0.2

United States Patent U.S. Cl. 148-3157 4 Claims ABSTRACT OF THE DISCLOSURE A permanent magnet is constituted of a body composed of fine particles of a compound M R in which M is cobalt or a combination of cobalt and one of the metals Fe, Ni or Cu and R is La Ce where O x 1.

This application is a continuation-in-part of application Ser. No. 644,101, filed June 7, 1967.

The invention relates to a permanent magnet constituted of fine particles having in themselves permanent magnetic properties. The component of these particles which is essential to these magnetic properties is M R where R is a combination of the two rare earth elements La and Ce, and M is either Co or a combination of Co with one or more of the elements Fe, Ni and Cu In the prior application permanent magnets are dis closed, the component of which is essential to the permanent magnetic properties is M R where 'M is cobalt or a combination of cobalt and one of the metals Fe, Ni and Cu and R is La, Th with a earth metal, or at leaset three rare earth metals. Such magnets have a high nniaxial anisotropy combined with a high saturation magnetization.

Permanent magnets also are required to have both a high saturation moment 0', and a high intrinsic coercive force, H

According to the invention a permanent magnet as described in the previous application has a component essential to the permanent magnetic properties a compound M 'R. R, however, now is La Ce Such a permanent magnet, according to the invention, may in particular have an H of more than 3500 oersteds (oe.) combined with a a of more than 30 erg/gauss oersted (g.-oe.) when 0 x 0.6.

When 0.2 x 0.6 a combination of H 3500 0e. and o' 90 (g.-oe.) are reached.

The invention will be described with reference to the accompanying drawing, the sole figure of which shows the dependence of H and 0' as functions of x.

"Graph 1 shows how, in a permanent magnet constituted of fine particles of compounds of the series La Ce C0 0 x 1, the value of H depends upon x.

The H values plotted in this graph are always the highest obtained values of a particular compound in the series. The H measured actually depends upon the size of the particles measured. By reducing these particles in size so that they increasingly show a single-domain-character, the H increases in principle. However, the reduction of the particles in size also involves a deformation. This may just have an opposite effect in various cases on the value of H however the H values from which Graph 1 was plotted have all been measured with an experimentally determined optimum average particle size.

Graph 2 shows the variation of the saturation magnitization 0' also as a function of x for the same series of compounds.

It is found that the values of both H,; and v for 0 x 1 differ substantially from what might be expected from what is known for these quantities for x=0 and x=1. With a suitable choice of x the manufactured permanent magnets may show combinations of 0 and H which are more favorable than those of the permanent magnets constituted of the compounds for which x=0 or 'x=1.

These magnets are made using the process described in the aforesaid application Ser. No. 644,101, viz., a body is first manufactured by melting the component elements to form the compound of M R and subsequentially the mass is cooled. The body is if necessary homogenized by annearling in an atmosphere which protects against oxidizing influence at a temperature just below the melting point. After being cooled to room temperature the body is pulverized and the powder molded into a body in a magnetic field.

While the invention has been described with reference to specific embodiments, other modifications will be apparent to those skilled in this art without departing from the spirit and scope of the invention which is defined in the appended claims.

What is claimed is:

1. A permanent magnet constituted of a body composed of fine particles having in themselves permanent magnetic properties and which consist of a compound M R, M being selected from the group consisting of Co and a combination of Co with at least one of the elements selected from the group consisting of Fe, Ni and Cu and R is La Ce 0 x 1.

2. A permanent magnet as claimed in claim 1 in which M is Co.

3. A permanent magnet as claimed in claim 1 in which 0 x 0.6, said magnet having an H exceeding 3500 cc. and a" exceeding 30 erg./g.-oe.

4. A permanent magnet as claimed in claim 1 in which 0.2 x 0.6, said magnet having an H exceeding 3500 cc. and a exceeding erg./g.-oe.

References Cited UNITED STATES PATENTS 2,813,789 11/1957 Glaser 75-123 3,102,002 8/1963 Wallace et a1 75-152 X 3,326,637 6/ 1967 Holtzberg et al. 75-152 X 3,342,591 9/1967 Gambino et al. 75-152 3,421,889 1/ 1969 Ostertag et al. 75-170 3,424,578 1/ 1969 Strnat et al 75-213 L. DEWAYNE RUTLEDGE, Primary Examiner G. K. WHITE, Assistant Examiner US. Cl. X.'R. 75-152, 148-101, 103 

